PreloadCheck class for extension pre-install checks

extensions/browser/preload_check.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef EXTENSIONS_BROWSER_PRELOAD_CHECK_H_
+#define EXTENSIONS_BROWSER_PRELOAD_CHECK_H_
+
+#include <set>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/strings/string16.h"
+
+namespace extensions {
+
+class Extension;
+
+// Encapsulates a possibly asynchronous operation to verify whether a
+// precondition holds for loading the given extension.
+class PreloadCheck {
+ public:
+  // These enumerators should only be referred to by name, so it is safe to
+  // insert or remove values as necessary.
+  enum Error {
+    NONE,
+    BLACKLISTED_ID,
+    BLACKLISTED_UNKNOWN,
+    DISALLOWED_BY_POLICY,
+  };
+
+  using Errors = std::set<Error>;
+  using ResultCallback = base::OnceCallback<void(Errors)>;
+
+  explicit PreloadCheck(scoped_refptr<const Extension> extension);
+  virtual ~PreloadCheck();
+
+  // This function must be called on the UI thread. The callback also occurs on
+  // the UI thread.
+  virtual void Start(ResultCallback callback) = 0;
+
+  // Subclasses may provide an error message.
+  virtual base::string16 GetErrorMessage() const;
+
+  const Extension* extension() { return extension_.get(); }
+
+ private:
+  // The extension to check.
+  scoped_refptr<const Extension> extension_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreloadCheck);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_PRELOAD_CHECK_H_